The invention relates to a device for damping rotary oscillations in a drive train, in particular for auxiliary units in a of a reciprocating piston internal combustion engine, with a freewheel clutch situated between a pulley and a hub. The hub is connected to an input shaft of an auxiliary unit and the pulley is connected to a crankshaft via a traction means. The freewheel clutch comprises an inner ring, which surrounds the hub and which is fixed thereto, and an outer ring, which surrounds the inner ring with radial play and which is fixed to the pulley.
Due to the increasing demands on the automotive industry to reduce average fuel consumption, for an internal combustion engine, for example, a belt-driven starter generator is used. This novel technology is used preferably in combination with gasoline or diesel engines with direct fuel injection. Due to the unfavorable driving gear dynamics that such engines exhibit, the desire has been suggested to be able to use a traction means drive with a generator-freewheel belt pulley (OAP, Overrunning Alternator Pulley). Here, the proven operation of a generator freewheel should be used.
Such a freewheel combined with a pulley is known, for example, from the publication DE 195 11 188 A1. Such a freewheel transmits the traction means drive moment generated by the crankshaft to an input shaft of the auxiliary unit. The freewheel belt pulley reduces the irregularities coming from the crankshaft, in that it partially “slips.” This behavior is undesirable for the use of a starter as an auxiliary unit. In this respect, this represents a special auxiliary unit since the moment is transmitted in the reverse direction from the auxiliary unit to the crankshaft. Therefore, it is necessary to lock the generator in rotation with the pulley in the starting phase.
On the other hand, after the starting phase, for optimal functioning of the generator, it is necessary to provide the most uniform drive possible for this generator, which can be realized via a freewheel. The solution presented in DE 44 34 324 to use a hydrostatic coupling to couple auxiliary units into a drive unit is unsuitable, because there is not necessarily any hydraulic pressure during the starting phase.